U.S. Pat. No. 1,923,567 discloses an ophthalmic mounting arrangement which allows individual prescription lenses to be selectively applied to goggles. Each prescription lens is separately manually positioned in or removed from clips which comprise part of the goggles. Since the prescription lenses must be handled directly during application or removal there is considerable likelihood that they will be damaged. Furthermore, the means for mounting the individual prescription lenses is an integral part of the goggle construction, considerably adding to goggle cost and complexity. There is no showing in U.S. Pat. No. 1,923,567 of an approach whereby prescription lenses may be readily applied to and removed from conventional sunglasses. U.S. Pat. Nos. 1,561,958 and 1,587,131 have similar deficiencies.
Applicant is also aware of prior art arrangements which purportedly convert spectacles or eyeglasses into a pair of sunglasses. This, of course, is quite opposed to the present arrangement which allows for the ready application of prescription lenses to sunglasses. In any event, U.S. Pat. No. 3,890,037 discloses an arrangement allowing for the attachment of tinted flexible plastic lenses to a pair of spectacles. More particularly, the lenses are individually press fit into the rear face of a spectacle frame. Such an arrangement requires individual manual handling of the tinted lenses and the spectacle frames must be machined in a highly precise manner to permit application of the tinted lenses. This, of course, greatly adds to cost. U.S. Pat. No. 3,427,098 also relates to a sun shade attachment for eyeglasses and the device disclosed therein suffers from the same deficiencies as the device shown in U.S. Pat. No. 3,890,037. Yet another arrangement of this same general type is disclosed in U.S. Pat. No. 4,338,004.
U.S. Pat. No. 4,070,103 discloses the use of lens rim covers which may come in a variety of sizes, shapes, and designs and which may be selectively attached to or removed from a conventional spectacle frame to provide different appearances.
Of even less pertinence to the present invention are the arrangements shown in U.S. Pat. No. 1,130,634 disclosing arrangement for attaching a shield to spectacles, U.S. Pat. No. 2,951,418 disclosing a complex corrective lens holder for a face mask, and U.S. Pat. No. Des. 203,949 disclosing a safety lens attachment design for eyeglasses.
By way of contrast with the arrangements disclosed in the above-identified patents, the apparatus of the present invention allows for the simultaneous application of two prescription lenses to sunglasses of conventional construction. The prescription lenses may be attached to or removed from the sunglasses without the user having to directly touch the prescription lenses, possibly causing damage thereto.
Furthermore, apparatus constructed in accordance with the teachings of the present invention is simple, light-weight and low cost. With the present approach, prescription lenses may be utilized in conjunction with a wide variety of sunglass styles, including popular designer styles. Only a very slight modification need be made to the sunglasses to permit their conversion to prescription lens use.